Does It Matter Where Stocker Steers Originate From? An Evaluation of Originating Environment on Performance and the Rumen Microbiome. Reynolds, A. Q. Ph.D. Thesis, ProQuest Dissertations Publishing, 2023. Book Title: Does It Matter Where Stocker Steers Originate From? An Evaluation of Originating Environment on Performance and the Rumen Microbiome ISBN: 9798379562151
Does It Matter Where Stocker Steers Originate From? An Evaluation of Originating Environment on Performance and the Rumen Microbiome [link]Paper  abstract   bibtex   
Growing stocker cattle on native rangelands is a viable agricultural enterprise for many ranchers as yearlings offer producers flexibility in management and marketing of the cattle. Grazing studies evaluating livestock performance across different rangeland ecosystems are extensive, and differences in weight gains across these studies can be attributed to genetics, environment, climate, management. However, the origin of cattle and its implications for producers is understudied. We compared performance of yearling steers originating from a local ranch in northeastern Colorado to yearlings originating from a high-elevation mountain ranch in southeastern Wyoming and a mixed-grass prairie ecosystem in south-central Nebraska. Forty steers of each origin grazed on the shortgrass steppe from mid-May to October with individual animal weights obtained at the beginning and end of each three grazing seasons (2019-2021). Weather patterns in 2019 and 2021 were similar, with spring precipitation followed by a dry late summer. In these years with normal precipitation, we observed consistent ordering of yearling steer weight gains by origin. In 2019 and 2021, local steers gained 1.08 and 0.96 kg/head/day, respectively. Weight gains of steers from the high-elevation ranch were 12 – 23% lower at 0.83 and 0.84 kg/head/day in 2019 and 2021, respectively. Yearlings from the mixed-grass prairie had 20 – 31% lower gains than local cattle at 0.75 and 0.76 kg/head/day in 2019 and 2021, respectively. Average daily gain of yearling steers was reduced 15 – 25% by drought in 2020, where forage quantity and quality were greatly impacted. Local cattle gains were 0.81 kg/head/day, which is 11% greater than gains observed in yearlings from the mixed-grass prairie. Diet quality, including measures of crude protein and digestible organic matter, did not differ among yearlings of different originating environments across the full grazing season in any year of the study. These data suggest that differences in weight gain of yearling steers could be attributed to physiological acclimation to a new grazing environment, lack of knowledge influencing grazing behavior, differences in digestive efficiency based on rumen microbial populations, or genetics that are not matched to grazing on the shortgrass steppe. To better understand the influence of origin on yearling steer ruminal microbial community structure and composition, rumen fluid was collected from 18 steers (n = 6 per origin) in each of the two non-drought years. Microbial DNA was extracted from the rumen fluid and 16S rRNA sequencing was completed on the Illumina MiSeq platform. QIIME2 was used to process reads, assign taxonomy, and compare samples utilizing alpha and beta diversity metrics as well as Analysis of Compositions of Microbiomes (ANCOM) to detect differences between originating environment, rangeland plant community, and sample period in each year. Differences in alpha diversity were observed within yearling steer origin and sampling date in richness and evenness Rangeland plant community did not influence differences in alpha or beta diversity measures. Ruminal microbial composition varied between origin in 2019 and differences in composition occurred between the early and late grazing season. In 2021, differences between originating environment were minimal, though compositional differences between early and late grazing were detected. Further investigation into the mechanisms by which originating environment influences performance of yearling steers could provide producers means to improve efficiency, as well as mitigate impacts of drought through optimally matching livestock to their grazing environment.
@phdthesis{reynolds_does_2023,
	title = {Does {It} {Matter} {Where} {Stocker} {Steers} {Originate} {From}? {An} {Evaluation} of {Originating} {Environment} on {Performance} and the {Rumen} {Microbiome}},
	shorttitle = {Does {It} {Matter} {Where} {Stocker} {Steers} {Originate} {From}?},
	url = {https://uwyo.primo.exlibrisgroup.com/discovery/fulldisplay?docid=cdi_proquest_journals_2817927109&context=PC&vid=01UOW_INST:quicksearch&lang=en&search_scope=MyInst_and_CI&adaptor=Primo%20Central&tab=Everything&query=any,contains,Does%20It%20Matter%20Where%20Stocker%20Steers%20Originate%20From%3F%20An%20Evaluation%20of%20Originating%20Environment%20on%20Performance%20and%20the%20Rumen%20Microbiome},
	abstract = {Growing stocker cattle on native rangelands is a viable agricultural enterprise for many ranchers as yearlings offer producers flexibility in management and marketing of the cattle. Grazing studies evaluating livestock performance across different rangeland ecosystems are extensive, and differences in weight gains across these studies can be attributed to genetics, environment, climate, management. However, the origin of cattle and its implications for producers is understudied. We compared performance of yearling steers originating from a local ranch in northeastern Colorado to yearlings originating from a high-elevation mountain ranch in southeastern Wyoming and a mixed-grass prairie ecosystem in south-central Nebraska. Forty steers of each origin grazed on the shortgrass steppe from mid-May to October with individual animal weights obtained at the beginning and end of each three grazing seasons (2019-2021). Weather patterns in 2019 and 2021 were similar, with spring precipitation followed by a dry late summer. In these years with normal precipitation, we observed consistent ordering of yearling steer weight gains by origin. In 2019 and 2021, local steers gained 1.08 and 0.96 kg/head/day, respectively. Weight gains of steers from the high-elevation ranch were 12 – 23\% lower at 0.83 and 0.84 kg/head/day in 2019 and 2021, respectively. Yearlings from the mixed-grass prairie had 20 – 31\% lower gains than local cattle at 0.75 and 0.76 kg/head/day in 2019 and 2021, respectively. Average daily gain of yearling steers was reduced 15 – 25\% by drought in 2020, where forage quantity and quality were greatly impacted. Local cattle gains were 0.81 kg/head/day, which is 11\% greater than gains observed in yearlings from the mixed-grass prairie. Diet quality, including measures of crude protein and digestible organic matter, did not differ among yearlings of different originating environments across the full grazing season in any year of the study. These data suggest that differences in weight gain of yearling steers could be attributed to physiological acclimation to a new grazing environment, lack of knowledge influencing grazing behavior, differences in digestive efficiency based on rumen microbial populations, or genetics that are not matched to grazing on the shortgrass steppe. To better understand the influence of origin on yearling steer ruminal microbial community structure and composition, rumen fluid was collected from 18 steers (n = 6 per origin) in each of the two non-drought years. Microbial DNA was extracted from the rumen fluid and 16S rRNA sequencing was completed on the Illumina MiSeq platform. QIIME2 was used to process reads, assign taxonomy, and compare samples utilizing alpha and beta diversity metrics as well as Analysis of Compositions of Microbiomes (ANCOM) to detect differences between originating environment, rangeland plant community, and sample period in each year. Differences in alpha diversity were observed within yearling steer origin and sampling date in richness and evenness Rangeland plant community did not influence differences in alpha or beta diversity measures. Ruminal microbial composition varied between origin in 2019 and differences in composition occurred between the early and late grazing season. In 2021, differences between originating environment were minimal, though compositional differences between early and late grazing were detected. Further investigation into the mechanisms by which originating environment influences performance of yearling steers could provide producers means to improve efficiency, as well as mitigate impacts of drought through optimally matching livestock to their grazing environment.},
	language = {eng},
	urldate = {2023-08-11},
	school = {ProQuest Dissertations Publishing},
	author = {Reynolds, Averi Q.},
	year = {2023},
	note = {Book Title: Does It Matter Where Stocker Steers Originate From? An Evaluation of Originating Environment on Performance and the Rumen Microbiome
ISBN: 9798379562151},
	keywords = {Terrestrial Ecoregions},
}

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